Loading and unloading packages, boxes, products, and/or other cargo items from the cargo spaces in trucks, trailers, semi-trailers, flat beds, cargo carriers, and the like can be quite expensive, labor-intensive, and even dangerous at times. Forklift trucks have been used to load pallets of items to and from semi-trailers, but there are a number of limitations on their use. For example, semi-trailers have been known to dislodge from loading docks which can be especially dangerous for forklift truck operators. Notably, one danger is trailer creep (also called “trailer walk” or “dock walk”), which occurs when the lateral and vertical forces exerted each time a forklift truck enters and exits the semi-trailer causes the semi-trailer to slowly move away from the dock. Eventually, the forklift may fall into the resulting gap caused by this separation of the semi-trailer from the dock leveler. Moreover, the pallets typically do not fill the entire cargo space such that there is still a significant amount of empty space. This wasted empty space costs money. Loading dock personnel have been used to manually unload and stack items within the cargo space, but such labor intensive activities can be quite expensive and can result in injury to the personnel.
Robotic and other automated systems have been proposed for loading and unloading cargo, but these systems still have a number of significant drawbacks. In a large number of automated or robotic systems, the majority of the weight of the robot as well as any ancillary conveyor equipment is supported by the floor of the semitrailer or other cargo space. Some semitrailers are unable to support such a heavy load, and even when it can support the weight, the movement of the robot as well as other equipment into the cargo space can result in dangerous trailer creep. Moreover, semi-trailers are sometimes not perfectly level and can be prone to shaking or even tipping as the relatively heavy robotic equipment moves. This shaking can lead to cargo being dislodged or falling down from the stack. During shipping as well as even loading by the robot, items can become shifted (e.g., boxes are tipped over); as such they are unable to be easily handled by robotic equipment. Consequently, human assistance is needed to stack or unload the shifted cargo items. By the automated robotic system occupying a significant amount of floor space, the human operator is unable to work alongside the robot. As a result, the robotic equipment has to be removed from the cargo space in order to allow the human operator access to the cargo. This in turn slows down the loading or unloading process. Moreover, other automated and robotic systems utilize a configuration similar to a forklift truck such that the system is unable to individually stack the cargo within the cargo space. With such a system, the cargo cannot be efficiently packed within the cargo space.
Thus, there is a need for improvement in this field.